How sensitive is MRI in the workup of ulnar neuropathy?

Updated: Jun 08, 2018
  • Author: Charles F Guardia, III, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

Several small studies have attempted to address the use of MRI in the diagnostic evaluation of ulnar neuropathy. Vucic et al identified 52 patients who met clinical criteria for ulnar neuropathy on the basis of either sensory symptoms or motor weakness in the distribution of the ulnar nerve; all underwent EP testing. [126] In 63%, the EP studies were diagnostic of an ulnar neuropathy at a specific location, commonly at the elbow. In 37%, the studies were nonlocalizing according to American Association of Electrodiagnostic Medicine criteria.

All 52 patients subsequently underwent MRI scanning as well, which revealed abnormalities in 90%. [126] Of those patients who had diagnostic EP studies, 94% had an abnormal MRI; of those who had nondiagnostic EP studies, 84% had an abnormal MRI. The authors concluded that MRI was “more sensitive” than neurophysiologic testing and that the sensitivity of MRI did not change, regardless of the EP results.

A study by Andreisek et al assessed 51 patients with clinically evident neuropathies in the radial, median, or ulnar nerve who were referred to their center for MRI scans of an upper extremity. [127] The aim of this study was to assess the impact of the MRI results on clinical decision making and patient management.

Andreisek et al found only a weak-to-moderate correlation between MRI results and clinical findings—not surprisingly, given that clinical findings imply physiologic dysfunction of the nerves, whereas MRI findings can evaluate nerve morphology alone. [127] The greatest use of MRI in this study seemed to be in cases where the cause of the symptoms was unclear; in this situation, MRI reportedly identified the symptom etiology in 93% of cases. This resulted in a moderate-to-major impact on treatment in 84% of the patients in this subgroup.


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